Combined electrical recorder and reproducer for phonographs



a" 1931- o. M. DUNNING COMBINED ELECTRICAL RECORDER AND REPRODUCER FOR PHONOGRAPHS Filed July 10, 1930 wkw- ORNEY O m ww W Y MB Patented Aug. 4, 1931 um'rsosrATEs PATENT OFFICE ORVIZLE MJDU'NNING, OF GRANGE, JERSEY, ASSIGNOR TO THOMAS A. EDISON, INCORPORATED, OF WEST NEW JERSEY, A CORPORATION OF NEW JERSEY COMBINED ELECTRICAL RECORDER AIJD REPRODUCER FOR PHONOGRAPHS Application filed July 10,

This invention relates to a combined electrical recorder andreproducer for phonographs; such for example, as dictating machines. v v

Suchm'ac'hines require to be reversible in operation since the operator may desire to dictate for a time and then may desire to have themachine reproduce what has been dictated. In the past, various arrangements have been suggested for rendering the diaphragm mechanism reversible where the recording and reproducing is done mechanically, that is to say where the sound waves actuate a diaphragm which in turn vibrates a stylus in recording or wherein a stylus vibrates a diaphragm and reproduces the sound waves. 7

WVhen, however, it is attempted to provide a single reversible mechanism for selectively recording and reproducing sound Waves electrically, that is to say, for converting the sounds to be recorded into electrical currents and utilizing such currents to vibrate an armaturewhich is connected to a stylus en.- ga-gingthe record, and for converting the recording into motion of an armature and thence into electrical currents, and thence into sound, certain ditficulties are encountered, particularly in attempting to realize in practice the maximum possible benefits of the electrical method of recording and reproducing. a

It has been found that the relative position ofthe stylus and record and the pressure eX- ertedby the stylus on the record should be difier'ent for recording and reproducing it best results in .each operation are to be obtained. Since it is impractical and inadvise able to change the armature and magnetic structure by substituting a recorder unit for a reproducer unit (commonly called a pickup) in changing from the recording to reproducing condition, the pickup and its associated stylus mechanismshould be arranged to fulfill as as possible in either the recording or reproducing positions the conditions which should obtain for optimum re-, sults. To this end ithas been suggested to make use of a sort of leverage or linkage arr ngement whi may e int rpos d between.

1930. Serial No. 466,902.

the stylus and the vibrating armature in changing from recording to reproducing position and which may be removed in returning again to recording position.

In my opinion, it is very difiicult to realize to the maximum the advantages inherent in electrical recording and reproducing when an adjustable linkage arrangement is interposed and removed. The diiliculties inherent in designing a linkage system-which will be acoustically and mechanically satisfactory and which will be practical and at the same time capable of quick shifting as required, are very great. In my opinion, best results are obtained when the adjustable linkage is dispensed with and when the pickup itself is so constructed and arranged and mounted upon a record that no change is required in changing from the recording to the reproducing position other than a change in position of the pickup.

It is an object of this invention to provide a simple electrical pickup apparatus which is so arranged as to be capable of functioning with high quality and efficiency either as a recorder or reproducer without any change in the pickup structure.

It is a further object of this invention to provide an arrangement of the class described which dispenses with adjustable linkages.

It is a further object of this invention to provide a pickup structure of the class de scribed which can be easily and quickly shifted from recording to reproducing position and vice versa.

' It is a further object of this invention to provide an arrangement of the class described in which the only change necessary to be made in changing from recording to reproducing position is a mere change in the position of the entire pickup apparatus.

It is a further object'of this invention to provide apparatus of the class described in which the predetermination and design of the apparatus itself provide for the optimum operating constants in either the recording or reproducing condition.

It is a further object of my invention to Provide pp ra u at he class descri ed which shall be simple, reliable, and positive in operation, even in the hands of an. unskilled operator.

Still other objects and advantages of my invention will be apparent from the specification. p I The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its fundamental principles and as to its particular embodiments, will best be understood by reference to the specification and accompanying drawings, in which Fig. 1 is a side view partially broken away of apparatus according to my invention in position for recording;

Fig. 2 is a similar view of the apparatus in position for reproducing, and

Fig. 3 is'a detail view on an enlarged scale of a modified form of apparatus according to my invention. I

Referring now-more particularly to Fig. 1, "1 designates the so-called pick-up unit which is; pivoted on an axis 2- and carried by a bracket 3 which is movable and which is ar- 7 ranged'in a manner with which I am not here concerned so as to permit of lifting the pickup ed the record,and of carrying the pickup along the record, either manually, or through feed screw mechanism not shown. For this purpose the arm 3 may be pivoted upon a support at asuitable point such as P and if desired suitable mechanism maybe employed forexerting pressure upon the lever S for the purpose of lifting the pickup off the record.

' The bracket 3 is provided with an angu larly projecting extension 4 whichmay be a spring arm pressing against the face of the pickup. A stud 5 may be provided on the face of the pickup and a depression 561. to receive the stud may be formed in the arm'l in such a manner that when the pickup is lifted off the record and rotated clockwise the stud 5 will force the arm 4: outwardly until the stud 5 passes intodepression 5a which serves tomaintain the angular position of the pick- .up with respect to the arm 3. 7

The detail of the electromagnetic structure of the pickup itself is not per se a part of this invention and I have therefore shown the same onlydiagrammatically, it being understood that any suitable electromagnetic or dynamic structure may be utilized. The form of pickup shown is one with which good results have been obtained but different forms in contact with the magnetic pole faces and extending toward each other. There is also provided a pair of upper pole pieces 11 and 12l1kewise in contact with the pole faces of the magnet and extending toward each other.

Gaps are left between the lower pole pieces 9and 10 and the upper pole pieces 11 and 12 and there is provided within these gaps a vibrating armature 15 surrounded by a winding or coil VV. The armature 15 may be'provided with central extensions 16 projecting from opposite sides thereof and defining the axis of vibration of the armature and the corresponding faces of the pole pieces 9 and 10 may be cut-away to hold the armature in position. Layers 17 of rubber, felt or similar damping material maybe interposed between the projection 16 and the pole pieces 9 and 10, and may also be interposed between the upper ends of the armature and the pole pieces 11 and 12.

Just below the axis of vibration the armature is preferably given a bend ofapproximately 90 as at point 16a and provided with two projections 18 and 19 at the extremities of which there may be mounted respectively the recoroing and reproducing styli or ewels 18a and 19a which engage the record;

The lower face of the pickup is provided witha downwardly projecting arm 6, the lower endof which hasa' spherical or other suitably shaped surface 7 adapted to enj the record which ismade large enough so that the recordis not appreciably marked by it.

In the position shown in Fig. 1 in which the recording'stylus 18 and'the advance ball 7 engage the record, the pickupis so placed relative to the record cylinder that when the advance ball and stylus are in contact with the record the center line of the pickup is approximately normal to the surface of the cylinder an displacedthrough an angle of about 20 from the vertical, and the various dimensions are so chosen that a vertical line passing through the center of gravity G intersects a line AR drawn'between the point of the advance ball 7 and the recording stylus 18aat point X. As more particularly ex plained and claimed in my'application, Serial No. 466,901, entitled Phonographic apparatus, filed concurrently herewith, the pressure on the recording stylus is then thatproportion of the weight of the unit equal to 42;. AR 7 Under such conditions when the recordrotates electrical currents supplied to the pickup are converted into vibrations of the recording stylus 18a and inscribed on the record. When the operator desiresa machine to reproduce it is only necessary to lift the pickup ofi the record and to rotate it clockwise ifiro1n the position shown in Fig. l tothe positionfihownin Fig. 2 in which stud 5 engages ,the depression 564 in arm 4 after which the I the reproducing stylus 19a.

pickup is lowered until the reproducing stylus 190; engages the record. The length of the stylus holders :18 and 19, the angular 1 position of the pickup in 170.1). the recording and reproducing positions are all so chosen and cont-rolled that in the recording position the entire .weight of the pickup is carried upon the advance ball 7 and the recording stylus 18a, and the reproducing stylus 19a does not engage the record, whereas under .the reproducing 'positionas shown in Fig. 2 both the advance ball 7 and the recording stylus 18a are out of contact with therecord and the reproducing stylus 19a is in engage- .rnent with the record.

In the recording position the angular positionof the pickup is controlled by the engagenientiof the advance ball and the stylus with the record, the pickup being free to take the proper position supported on these two points. In the reproducing position however sinceonly the reproducing stylus is in engagement with the record, it is necessary that the pickup be-locked in position with respect to arm '3 which is done by engagement of stud 5 with depression 542; It will be noted that in the reproducing position since no upward force'is exertedonthe pickup by the arm 3 the weight of the pickup is carried upon-only the reproducing stylus, whereas in the recording position the weight is distributed between the advance ball and the recording stylus whereby a very much less pressure is exerted upon the recording stylus which is the desired condition forbest results. :ESince the pressure on the recording stylus can be nedueed very materially by proper choice of the fraction AR as already pointed-out, by -chang ing the position of the advance ball 7 or the recording stylus 18a, or both, or by changing the angle of the pickup in recording positiomthe pickup may be made as he; vy as desired in order to obtain the best results in the reproducing condition, while at the same time the desired 7 pressure on the recording stylus may be maintained as small as desired.

In the arrangement shown in Figs. 1 and 2 it will be observed that the recording stylus 18a is closer to the pivot of the armature than Consequently, if a record which has been made by the recorder stylus is played with the pickup in reproducing position, the reproducing stylus will bevibrated through the same amplitude I which was traversed by the recording stylus,

but since the reproducing stylus is further from the pivot, but since the reproducing stylus is further from the pivot, the motion of the armature will not be so great in reproducing as it was in recording.

Under some conditions it may be desired to provide for an increase of the ratio of motion of the armature over the arrangement shown in 1. This may be accomplished by the arrangement shown in Fig. 3, in which the reproducer stylus 19a is not mounted upon an extension of the arm 16 but in this case is mounted upon a separate lever 20' which in turn pivoted on bracket 21 mounted on the pickup in such position that when the pickup 1s in reproducing position on the record, the end of lever '20 engages the upper sideof the arm 16.

It will be observed that when the pickup is placed in reproducing position on the rec old, the weight of the unit tends to rotate the lever 20 counter clockwise in bracket 21 and thereby tends to rotate the arm 16 clockwise. As the stylus 19a is vibrated by the record .the vibrations are thus transferred to the lever 16 and if lever 20 is pivoted oif center, for example, as shown, the amplitude of the vibrations of the stylus will he multiplied before being transmitted to the lever 16. v v

lVhile I have shown and described certain preferred embodiments of my invention it will be understood that modifications and changes may be made without departing vance ball and said recording stylus engage said record, and in the other said reproducing stylus only engages said record.

2. A combined electrical sound reeerder and reproducer unit, comprising, in combination, a frame, a recording stylus carried by said frame, a reproducing stylus carried by said frame, reversible means for converting electric curren's into mechanical vibrations associated with said styli, said styli being positioned on the same side of one faceof said unit, an advance ball positioned on the opposite side of said face of said unit, and means for selectively maintaining said unit with said advance ball and recording stylus in engagement with said record, or with said reproducing stylus in engagement with said record.

3. A combined electrical sound recorder and reproducer unit comprising, in combination, a frame,a vibratile arm carried by said arm, a reproducing stylus carried by said arm, reversible means for converting electric currents into mechanical vibrations associated with said arm, an advance ball mounted on said frame, and means for selectively maintaining said unit with said reproducing stylus only in engagement with a record, or with said recording stylus and said advance ball in contact with said record.

4. A combined electrical sound recorder and reproducer unit, comprising, in combination, a frame, a vibratile arm carried by said frame, a recording stylus carried by said arm, a reproducing stylus carried by said arm on a different part thereof, reversible means for converting electric currents into mechanical vibrations, associated with said arm, an advance ball mounted on said frame, and means for selectively maintaining said unit in clifferent angular positions on a record, in one of which said reproducing stylus only engages said record, and in the other both said recording stylus and said advance ball en- 7 gage sald record.

5QA combined electrical sound recorder and reproducerunlt comprising, in combination, a frame, a recording stylus carried by said frame, a reproducing stylus carried by said frame, reversible means for converting electric currents into mechanical vibrations record.

6. A combined electrical sound recorder and reproducer unit comprising, 1n combmation, a frame, a recording stylus carried by said frame, a reproducing stylus carried by said frame, reversible means for converting electric currents into mechanical vibrations associated-with said styli, said styli being disposed on one side of the center line of said unit, an advance ball positioned on said frame on the other side of said center line, and means for selectively maintaining said unit in'two playing positions on a record, in one of which said recording stylus and said advance ball engage said record, and in which a vertical line passing through the center of gravity of said unit intersects a line projected between said advance ball and said recorder stylus, and in the other of which said reproducing stylus only engages said record,

7. combined electrical sound recorder and reproducer unit, comprising, in combination, a frame, a recording stylus carried by said frame, a reproducing stylus carried by said frame, reversible means for converting electric currents into mechanical vibrations associated with said styli, an atlvance ball mounted on said frame, said advance ball and said styli being positioned on opposite sides of the center line of said unit and means for selectively maintaining said unit in two different playing positions on a record with either of said styli engaging said record and with said advance ball engaging said record in recording'position, said unit in recording position being disposed with its center line at an angle to a vertical line passing through its center of gravity. 7

8. A combined electrical sound recorder and reproducer unit comprising, in combination, a frame, a vibratile arm carried by said frame, a recording stylus mounted on said arm, reversible means for converting electric currents into mechanical vibrations'associated with said arm, a vibratile'lever pivoted on said frame, a reproducing stylus mounted on said lever arm, said lever having its free end engageable with said arm in reproducing position, an advance ball mounted on said frame, and means for maintaining said unit in a plurality of playing positions on a record, in one of which said advance ball and'said recording stylus engage said record, and in the other of which said reproducing stylus only engages said record. V 1

9. A combined electrical sound recorder and reproducer comprising, in combination,

a' frame, a'vibratilearm carried by said frame, a recording stylus mountedon said arm, reversible means for converting electric currents into mechanical vibrations assoiated with said arm, a vibratile lever carried by said frame, a reproducing stylus mounted on said lever, and said lever having a portion developing larger amplitudes of motion than said reproducing stylus in driving relation with said arm in reproducing position, an advance ball on said frame and means for maintaining said unit in playing position on a record with said reproducing stylus only in engagement with said record, or with said recording stylus and said advance ball in engagement with said record. I This specification signed this 9th day 0 July, 1930.

ORVILLE M. DUNNING. 

